[jira] [Updated] (FLINK-7407) Assumption of partition id strict contiguity is too naive in Kafka consumer's AbstractPartitionDiscoverer

["Tzu-Li (Gordon) Tai (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-7407?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tzu-Li (Gordon) Tai updated FLINK-7407:
---------------------------------------
    Priority: Critical  (was: Major)

> Assumption of partition id strict contiguity is too naive in Kafka consumer's AbstractPartitionDiscoverer
> ---------------------------------------------------------------------------------------------------------
>
>                 Key: FLINK-7407
>                 URL: https://issues.apache.org/jira/browse/FLINK-7407
>             Project: Flink
>          Issue Type: Improvement
>          Components: Kafka Connector
>    Affects Versions: 1.4.0
>            Reporter: Tzu-Li (Gordon) Tai
>            Priority: Critical
>             Fix For: 1.4.0
>
>
> In the Kafka Consumer's {{AbstractPartitionDiscoverer}}, for partition discovery, already discovered partitions are tracked with the following map:
> {code}
> Map<String, Integer> topicsToLargestDiscoveredPartitionId
> {code}
> Simply put, on each discovery attempt's metadata fetch, all partition ids of a given topic that are smaller than the largest seen id will be ignored and not assigned. This approach lies on the assumption that fetched partition ids of a single topic are always strictly contiguous starting from 0.
> This assumption may be too naive, in that partitions which were temporarily unavailable at the time of a discovery would be shadowed by available partitions with larger ids, and from then on would be left unassigned.
> We should redesign how the {{AbstractPartitionDiscoverer}} tracks discovered partitions by not relying on the contiguity assumption, and also add test cases for non-contiguous fetched partition ids.



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